Digital cellular, and other radio, communication systems are deployed to encompass significant portions of the populated areas of the world. For many, access to such a communication system is a practical necessity. Two-way communications are generally provided in a cellular communication system to effectuate both voice communication services and data communication services.
A cellular communication system makes relatively efficient use of its allocated bandwidth, i.e., the portion of the electromagnetic spectrum allocated to the communication system for communications between the network infrastructure and a mobile station used pursuant to effectuation of a communication service. The geographical area encompassed by the cellular communication system is divided into parts referred to as cells, each defined by a base transceiver station. Relatively low-power signals are generated to effectuate communications between a base transceiver station and a mobile station positioned within the associated cell. And, cell-reuse schemes are utilized in which the same channels are re-used in different ones of the cells according to a cell re-use pattern or scheme. While channel allocations made pursuant to a cell re-use scheme are made to limit interference between concurrently-generated signals in the different cells, interference, sometimes occurs. Interference includes both co-channel interference and adjacent channel interference. If the interference is significant and it is not suppressed, or otherwise compensated for, the interference degrades communication performance of the receiving station.
Co-channel interference refers to interference caused by concurrently-generated signals sent in another cell that uses, i.e., “re-uses”, the same channels as those channels used in the cell in which the interfering signals are detected. And adjacent-channel interference refers to interference caused by concurrently-generated signal sent, typically, in another, e.g., adjacent, cell that uses different channels. But, the signal strengths of the signals sent in such other cells is so great as to cause aliasing that results in interference.
Various mechanisms are used, and others proposed, by which to compensate for interference included in a receive signal received at a receiving station. For instance, use of an adaptive noise whitening filter (INWF) has been proposed to suppress interference. The INWF is used together with a receive filter. The receiver filter has a passband wide enough to pass some adjacent channel interference and the INWF operates to whiten the interference. While a narrow receiver filter would reject greater amounts of adjacent channel interference, its narrowing worsens equalizer operation at the receiving station to compensate for co-channel interference.
In short, the use of the adaptive input noise whitening filter in a manner best to suppress adjacent channel interference competes with the ability of other receive-station elements to suppress, or compensate for co-channel interference. There is a need therefore, to provide an improved manner, at a receiving station, to compensate for, or to suppress, interference forming part of a receive signal received at a receiving station.
It is in light of this background information related to receiving stations operable in a radio, or other, communication system that the significant improvements of the present invention have evolved.